If you're testing the phone's Wi-Fi speed, at best it will be the same as whatever your home's connection speed is. For the most part, the only thing that will slow it down is if there is too much distance between your phone and your router. 5 to 10 feet of distance (with nothing but air between the two) is ideal.

I've tested my cellular speed a few times, but the results are always quite varied. It usually does what I need in a reasonable amount of time, so I don't normally give it much thought. I'm currently at work, where my Moto X's Wi-Fi tested at 18 down; 24.5 up. The cellular bombed at 1.8 down; .72 up (I'm in the basement).